1. Field of the Invention
This invention relates to a composition containing a radical-polymerizable olefinically unsaturated compound and a hydrazone of an aromatic aldehyde or ketone. The invention also relates to its production and to its use as an adhesive and sealing compound and to its use for the coating and production of plastic moldings. The compositions according to the invention polymerize radically at room temperature.
2. Discussion of Related Art
For curing by peroxides or hydroperoxides, olefinically unsaturated systems require selected initiators or activator systems particularly when the reaction is to be initiated at low temperatures, for example at room temperature or only slightly elevated temperatures. For example, it is known that selected tertiary amine compounds with partial aromatic substitution at the N atom perform such an activating function. Known activators for initiating polymerization, for example with dibenzoyl peroxide, are in particular dimethyl aniline and dimethyl-p-toluidine.
A totally different known class of activators for oxidatively initiating the polymerization of certain unsaturated systems, namely drying oils, are metal compounds--at least partly soluble in the system--of metals which can occur in several valency stages and which accelerate the initiation reaction via intermediately occurring valency shifts on interaction with other components of the system. Metal compounds of such metals which are adequately soluble in organic solvents and/or in binders have long been known as so-called drying agents for the air drying of paints, varnishes and the like based on unsaturated oils. Sufficiently oil-soluble compounds of transition metals which are capable of occurring in several valency stages are particularly suitable for this purpose. The individual components differ considerably in their ability to accelerate hardening. Compounds of cobalt and/or manganese are particularly suitable, although iron also has an accelerating effect on curing. In addition, comparable compounds of other metals, which are also capable of developing several valency stages, may be used, particularly in combination with these highly effective metallic components. A detailed description of such systems can be found, for example, in "Ullmann, Encyklopadie der technischen Chemie", 4th Edition, Vol. 23 (1983), 421 to 424.
U.S. Pat. Nos. 4,010,152 and 4,063,012 describe the (co)polymerization of ethylenically unsaturated monomers, such as vinyl chloride, with selected aliphatic alphahydroperoxy)-azo compounds or salts thereof which, on the basis of the structural formulae provided, may be assigned to the class of hydrazone derivatives and which may be regarded as selected hydrazone peroxides. According to the teaching of the first of these two documents, they are prepared by reaction of alpha-halo-azo compounds with sodium peroxide or hydrogen peroxide in the presence of acid acceptors and are said then to be used to initiate polymerization. The majority of the Examples of this document and the parallel second U.S. patent cited above describe the production of the hydroperoxide compounds by a method which is not explained in detail in the general description of the invention. The particular hydrazone compounds selected are dissolved in a solvent and aerated with a stream of oxygen by passing the oxygen through the solution of hydrazone compounds kept at room temperature or at slightly elevated temperatures. The particular hydroperoxides are obtained in yields of 80% or more and are optionally purified by low-temperature crystallization. The hydroperoxides may be used as initiator systems for the polymerization of, for example, vinyl chloride or unsaturated polyester/styrene resins.
A number of earlier publications is concerned with compounds of this type and with their formation, in particular by autoxidation. In 1914, M. Busch et al. described the autoxidation of hydrazones in Ber. 47 (1914), 3277 to 3291. The alleged formation of the peroxides is formulated here as the addition of an oxygen molecule onto the C:N double bond of the hydrazone to form a four-membered peroxide ring. The autoxidation of phenyl hydrazones is also described in K. H. Pausacker, J. Chem. Soc. 1950, 3478 to 3481. This Article discusses the non-catalyzed reaction of pure phenyl hydrazines and the corresponding reactions with addition of a small quantity of benzoyl peroxide as a catalyzed reaction. A more detailed structural elucidation of the constitution of hydrazone peroxides is provided by R. Criegee et al. in Ber. 84 (1951), 219 to 224 where it is shown that the hydrazone peroxides can only be formed from derivatives of hydrazine compounds which still contain a hydrogen atom at the substituted N atom, at least at room temperature or correspondingly low temperatures.
U.S. Pat No. 4,855,373 describes trifunctional hydrazones, namely aliphatic and aromatic hydrazones of 1,3,5-tris-acetyl benzene, as an initiator for the polymerization of vinyl compounds. Acrylic acid and acrylic acid amides and esters with C.sub.1-4 alcohols are preferably polymerized with 1,3,5-tris-(acetyl-t-butylhydrazonyl)-benzene. The polymerization takes place in the presence or absence of atmospheric oxygen, its removal being preferred. The acrylic acid, of which the aqueous solution has been purged with nitrogen, polymerizes in 30 seconds on addition of a hydrazone solution (see Example 1). If the solution is not purged with nitrogen, no polymerization takes place for 2 minutes, but presumably does proceed in the event of subsequent purging with nitrogen. Accordingly, polymerization begins immediately after the vinyl monomers and the hydrazone compounds have been mixed.
Earlier patent application DE 40 00 776 describes hydrazone compounds corresponding to the following general formula as an initiator or as the principle component of an initiator system for curing olefinically unsaturated compounds by radical polymerization with ambient air: ##STR1## in this formula, R.sub.1, R.sub.2 and R.sub.3 are at least partly the same or different and have the following meanings:
R.sub.1 is a linear, branched or cyclic and optionally substituted alkyl radical or an optionally substituted aryl radical, PA1 R.sub.2 is hydrogen, a linear, branched or cyclic and optionally substituted alkyl radical or an optionally substituted aryl radical; PA1 R.sub.1 and R.sub.2 together with the co-substituted carbon atom may also form a cycloaliphatic radical which may even be substituted, PA1 R.sub.3 is a linear, branched or cyclic and optionally substituted alkyl radical or an optionally substituted aryl radical. PA1 R.sub.1 is hydrogen or an alkyl group containing up to 40 carbon atoms and PA1 R.sub.2 independently of the other substituents is hydrogen or an aromatic or aliphatic group containing up to 40 carbon atoms. PA1 1. stabilization against oxygen by addition of antioxidants and PA1 2. stabilization against radicals by addition of radical inhibitors. PA1 hydrazone compounds: at least about 0.1% by weight, preferably 0.5 to 7.5% by weight and more preferably 1 to 4% by weight PA1 soluble metal compound: 0 to 5% by weight, preferably 0,005 to 1% by weight and more preferably 0.1 to 5% by weight PA1 deoxidizer: 0 to 5% by weight and preferably 0.01 to 1% by weight. PA1 Mixtures of oligomers and/or polymers together with ethylenically unsaturated monomers of low molecular weight are used as the mixtures of radical-polymerizable compositions suitable for a wide variety of practical applications. The relatively high molecular weight components of the mixtures are often at least partly soluble in the monomers. Mixtures of this type are particularly suitable for processing in accordance with the invention. The content of monomers, for example of the (meth)acrylate, optionally substituted styrene and/or acrylonitrile type, is generally at least 10% by weight and preferably at least about 20% by weight and in many cases, may even be at least about 40% by weight (based on the reactive mixture as a whole). The monomer component may be by far the predominant component in terms of weight, so that for example 60 to 80% by weight of the mixture as a whole can be made up by the low molecular weight monomer. As previously explained, however, it is important to bear in mind the fact that the use of an adequate quantity of compounds of relatively high molecular weight and/or other thickening agents guarantees the at least slightly increased initial viscosity of the mixtures for safely initiating the reaction on exposure to air.